应用于牙种植力学分析的下颌骨材料赋值问题研究

目的：本文考察牙种植有限元分析中下颌骨模型材料赋值分别采用模拟患者骨质精确化赋值和均匀赋值后的生物力学情况和特点。方法：采用螺旋CT扫描,mimics软件逆向建立下颌骨三维模型和推导精确化赋材料参数公式,在有限元软件中装配有限元模型并模拟咬合力加载,分析种植体对于下颌骨应力分布情况。结果：两种不同处理情况下的下颌骨应力分布有较大不同点,真实病例牙列缺损部分赋值材料应力值明显低于均匀赋值材料的属性。结论：相对均匀赋值法,采取精确化赋值应力大致反映患者真实的应力情况,对于口腔医师针对具体病例术前研究和术后评价具有更高的借鉴性。     

Effects of diabetes on the osseointegration of dental implants

The increased prevalence of diabetes mellitus has become a public health problem. Hyperglycaemia entails a rise in the morbidity and mortality of these patients. Although a direct relationship with periodontal disease has already been shown, little is known about the results of dental implants in diabetics. The present paper reviews the bibliography linking the effect of diabetes on the osseointegration of implants and the healing of soft tissue. In experimental models of diabetes, a reduced level of bone-implant contact has been shown, and this can be reversed by means of treatment with insulin. Compared with the general population, a higher failure rate is seen in diabetic patients. Most of these occur during the first year of functional loading, seemingly pointing to the microvascular complications of this condition as a possible causal factor. These complications also compromise the healing of soft tissues. It is necessary to take certain special considerations into account for the placement of implants in diabetic patient. A good control of plasma glycaemia, together with other measures, has been shown to improve the percentages of implant survival in these patients.     

A comparison of written and multimedia material for informing patients about dental implants

A study was undertaken to compare the effectiveness of an information leaflet with a multimedia program in informing potential implant patients attending a dental hospital. The results show that both methods of presenting information are effective in informing patients; however, where the information to be presented is visual in nature, a multimedia presentation can have a more positive short-term effect than an equivalent leaflet.     

改变摩擦系数对固位螺丝稳定影响的实验研究

目的探讨摩擦系数的减小对种植体固位螺丝松动的影响.方法用32Ncm将种植体和基台用固位螺丝固定在支持物上,涂布凡士林于固位螺丝表面.保持静止状态和放进超声波震荡器中1h对比,用FG-101数显力矩扳手握住螺丝刀将每个固位螺丝松动,记录测量读数最大值.结果旋松扭矩分别为静止对照组26.7±2.00Ncm,实验组25±1.15Ncm;运动对照组26.1±1.20Ncm,实验组24.8±0.70Ncm.实验组比对照组的旋松扭矩小,两两比较有统计学意义(P＜0.05).结论基台和固位螺丝之间的摩擦系数减小,预负荷增加,但更易松动.     

两类传感器对种植体共振频率测量值影响的三维有限元研究

研究背景：共振频率法被认为是目前相对理想的测量种植体稳定性的方法。共振频率仪的测量传感器分为L型传感器和无线式铝杆传感器两类,然而,目前种植领域尚不清楚这两类传感器所测量的种植体共振频率值有何异同。目的：采用三维有限元法研究在不同骨质类型和不同种植体长度情况下,L型传感器和铝杆传感器两种设计对种植体共振频率测量值的影响。方法：（1）建立种植体-传感器-下颌磨牙区骨块三维有限元模型（ANSYS5.6软件）。种植体尺寸：直径固定为4.0mm,长度分4个等级：8.0mm、10.0mm、12.0mm和14.0mm;传感器分为两类：L型（高度22.0mm）和铝杆型（高度11.5mm）;模拟了3种骨质类型,即D2、D3和D4骨质。（2）在本质上,种植体一阶弯曲振动模态下的固有频率与共振频率仪所测量的共振频率相同,因此本研究直接采用有限元软件计算不同参数条件下种植体-骨块复合体的一阶固有频率。结果：（1）L型传感器组种植体的频率值在3763～4464Hz之间（平均4235Hz）,而铝杆模型种植体的频率值在9192～10002Hz之间（平均9708Hz）。（2）骨质由D4变为D2时,L型传感器组种植体的频率值增加百分比在12.7～16.7%之间（平均14.9%）,铝杆传感器组的增加百分比在7.4～8.5%之间（平均7.9%）。（3）对于L型传感器组而言,长度增加其频率值逐渐增加,14.0mm与8.0mm相比,频率值平均增幅为3.2%,对于铝杆传感器而言,D3骨质模型的频率值随长度增加而增加,在D4和D2骨质条件下,频率值呈先升后降（变化幅度较小）。（4）在D3骨质情况下,L型传感器测量值和铝杆传感器测量值之间存在线性相关,具有显著性（Pearson相关系数r=0.996,P=0.004）;在D4骨质情况下,L型传感器测量值和铝杆传感器测量值之间存在负相关关系,但是没有统计意义（r=-0.846,P〉0.05）;在D2骨质情况下,两组数值存在正相关关系,但同样没有统计意义（r=0.736,P〉0.05）。结论：在相同骨质类型、相同种植体尺寸条件下,L型传感器模型的频率值远小于铝杆传感器模型的频率值;L型传感器反映骨质变化的灵敏度高于铝杆传感器;在D3骨质条件下,两种传感器均能反映出测量值随长度增加而增加这一趋势     

Saliva and dental implants

This is a review and update of the: (1) interaction of dental implants with the environment, and (2) effects of salivary contamination on the load of implant prostheses.     

Tobacco and dental implants

Dental implants are the ideal standard of care for many oral health care providers. Tobacco use is an impediment to the success of this sophisticated procedure. Dentists who are trained to help their patients stop using tobacco are in position to improve their success rates with dental implants. A suggested protocol for tobacco cessation in the implant practice, if utilized, could raise the standard of health care in the dental office.     

改良喷砂表面处理对钛牙种植体骨结合的组织学作用

研究改良喷砂表面处理对钛牙种植体骨结合的影响。方法柱状纯钛种色植分两组（光滑表面和改良喷砂表面组）进行表面处理,植于狗后肢股骨内侧髁,分别于2、4、12周取材、固定、脱钙后常规HE染色,光镜观察。结果：改良喷砂表面组与光滑表面组的骨愈合过程,均为膜内成骨,并形成完全的骨结合。二者的差别主要表现在愈合的早期（割周）,改良喷砂表面组界面成骨较快,愈合中晚期差别不明显。结论：改良喷砂表面处理可以加快钛牙种植体的骨结合速度。     

Influence of implant taper on the primary and secondary stability of osseointegrated titanium implants

Objectives: The study presented was designed to analyse the mechanical performance and the primary and secondary stability characteristics of endosseous titanium implants with 1° (EXP1) and 2° (EXP2) of taper when compared with the standard Brånemark design (Nobel Biocare AB, Gothenburg, Sweden). Materials and methods: One pair of 10 mm EXP1 and control implants were placed in the femoral condyles of six rabbits. Paired 6 mm EXP1 and control implants and 6 mm EXP2 and control implants were placed in the tibial metaphysis. The control implants used were 4 mm diameter standard Brånemark implants, the same length as the test implants. At placement, insertion torque (IT) and resonance frequency analysis (RFA) measurements were performed. Six weeks postoperatively when the animals were killed, RFA and removal torque (RT) measurements were made. Results: At placement, significantly higher IT was needed to insert the EXP implants compared with the controls. RFA values were significantly higher for EXP1 implants placed in the tibia but not in the femur. In pooling data from the femur and tibia there was a significant difference. The EXP2 implants failed to insert fully and demonstrated a lower RFA value than may have been expected due to the exposed threads, although this difference was not statistically significant. Conclusions: The results from the present study showed that 1° of taper results in a better primary stability compared with the standard Brånemark design. There was no evidence that the tapered design caused negative bone tissue reactions. All the implants gained in stability during the healing period.     

种植义齿的骨感知现象及研究

一、种植体骨感知理论的提出及涵义Brfinemark在1965年提出了骨结合（osseointegration）的概念，从而开启了骨结合理论研究和现代种植学的大门，牙种植技术如今已经被广泛开展。上世纪九十年代。骨结合理论开始被用于截肢后的假肢修复，发现种植体假肢患者具有很好的肢体运动控制能力、本体感觉和反馈，这引起了研究者关注。拇指切除采用种植支持义指修复的患者，其触觉辨别能力达到了正常拇指触觉能力的80％，这提示一定有某种特殊的感觉传导机制存在。     

The effect of various thread designs on the initial stability of taper implants

STATEMENT OF PROBLEM

Primary stability at the time of implant placement is related to the level of primary bone contact. The level of bone contact with implant is affected by thread design, surgical procedure and bone quality, etc.

PURPOSE

The aim of this study was to compare the initial stability of the various taper implants according to the thread designs, half of which were engaged to inferior cortical wall of type IV bone (Group 1) and the rest of which were not engaged to inferior cortical wall (Group 2) by measuring the implant stability quotient (ISQ) and the removal torque value (RTV).

MATERIAL AND METHODS

In this study, 6 different implant fixtures with 10 mm length were installed. In order to simulate the sinus inferior wall of type IV bone, one side cortical bone of swine rib was removed. 6 different implants were installed in the same bone block following manufacturer''s recommended procedures. Total 10 bone blocks were made for each group. The height of Group 1 bone block was 10 mm for engagement and that of group 2 was 13 mm. The initial stability was measured with ISQ value using Osstell mentor® and with removal torque using MGT50 torque gauge.

RESULTS

In this study, we found the following results. 1. In Group 1 with fixtures engaged to the inferior cortical wall, there was no significant difference in RTV and ISQ value among the 6 types of implants. 2. In Group 2 with fixtures not engaged to the inferior cortical wall, there was significant difference in RTV and ISQ value among the 6 types of implants (P < .05). 3. There was significant difference in RTV and ISQ value according to whether fixtures were engaged to the inferior cortical wall or not (P < .05). 4. Under-drilling made RTV and ISQ value increase significantly in the NT implants which had lower RTV and ISQ value in Group 2 (P < .05).

CONCLUSIONS

Without being engaged to the inferior cortical wall fixtures had initial stability affected by implant types. Also in poor quality bone, under-drilling improved initial stability.     

Growth of bioactive surfaces on dental implants

Some metallic materials, such as pure titanium, Ti-6Al-4V, are used for dental and orthopedic implants under load-bearing conditions. However, they do not form a chemical bond with bone, which would achieve a good implant-bone fixation in service. In recent works, it has been demonstrated that an in vitro, chemically deposited, bone-like apatite layer with bone-bonding ability could be induced on a titanium surface. By reproducing that chemical procedure, in this work, a dense bone-like apatite layer was formed on the surface of the titanium in simulated body fluid. In addition, the different steps and kinetics of the layer-formation have been studied, because the observation of the samples in the wet state by means of the environmental scanning electron microscope has allowed the observation in situ of the apatite deposition process over a number of days. One of the most important features of the present study is that it can be carried out on a single titanium sample and the process is not interrupted at any stage. One of the main drawbacks of this chemical method is that the samples covered with apatite are susceptible to contamination by bacteria. The behavior of different types of antibiotics used to avoid this contamination has also been studied using the environmental scanning electron microscope. Finally, osteoblast cells have been cultured on the apatite-coated titanium samples to assess their biocompatibility.     

Identification of dental implants on radiographs.

In the future, dentists will more frequently encounter patients who have dental implants. To use radiographs to identify implants that were previously inserted by other dentists, dentists have to be familiar with the detailed morphology of different products and types of fixtures as well as with the principles for formation of their radiographic images. In the present study, radiographic images of ten common dental implants were analyzed. Images varied with viewing angles. The influences of surface structures, such as threads, cuts, holes, perforations, and flutes, are demonstrated.     

Single tooth replacement by Morse taper connection implants: a retrospective study of 80 implants.

The goal of this study was to provide data relative to the use of a new implant system (Mac System, Cabon, Milan, Italy) with a Morse taper implant-abutment connection for single implant restorations. The implant system is composed of an endosseous screw made of commercially pure titanium grade 2, while the abutment is titanium alloy (Ti-6Al-4V). A total of 80 single implants were placed in 69 patients (36 women and 33 men, mean age 42 years, range 16 to 61). All patients gave their informed consent and received a thorough clinical and radiographic examination. Smokers and diabetics were excluded from the study. Three implants were placed in areas of previous tooth impaction, 5 were placed in posttraumatic edentulous areas, 2 were used in situations involving tooth agenesis, and 60 replaced teeth lost because of caries or periodontal disease. All patients were edentulous for at least 1 year prior to treatment. The implants received a definitive prosthesis and had been in function for a mean period of 3.5 years. At second-stage surgery, 2 implants were removed because of lack of osseointegration. After 2 years of loading, 1 implant showed evidence of peri-implantitis and was removed. In addition, 2 fractured abutments and 1 loosened abutment were observed. Few mechanical or infectious complications were seen, and this may have been the result of high stability of the conical connection.